TWI635624B - Semiconductor light emitting element and method of manufacturing same - Google Patents

Abstract

The present invention provides a semiconductor light-emitting device which can obtain a light extraction efficiency with high light extraction efficiency even when the light-emitting wavelength is short, and a method of manufacturing a semiconductor light-emitting device which can manufacture the semiconductor light-emitting device with high reproducibility and high yield. The semiconductor light emitting element is a semiconductor light emitting element having a semiconductor layer including a light emitting layer, and the surface of the semiconductor light emitting element includes a light extraction surface. At least one of the interfaces of the two layers having different refractive indices in the light extraction surface and the semiconductor light emitting element is formed with a periodic uneven structure having a period larger than 0.5 times the wavelength of light emitted from the light emitting layer; and fine The uneven structure is located on the surface of the periodic concavo-convex structure and has an average diameter of 0.5 times or less of the wavelength of light.

Description

Semiconductor light emitting element and method of manufacturing same

The present invention relates to a semiconductor light-emitting element such as a light-emitting diode (LED), and more particularly to a semiconductor light-emitting element for improving light extraction to the outside through light emitted from the element, and a method of manufacturing the same.

The semiconductor light emitting element is formed of a plurality of layers such as a light emitting layer, an n-type semiconductor layer, a p-type semiconductor layer, an electrode layer, and a supporting substrate. Therefore, the light emitted from the light-emitting layer inside the semiconductor element is taken out to the outside through these several layers. However, with regard to light, when passing through the boundary of a medium having a different refractive index, that is, a layer interface, a surface, or the like, a predetermined ratio of reflection must occur. Further, when light passes through a dielectric layer having an absorption coefficient for the wavelength (light emission wavelength) of the light or is reflected, light absorption of a predetermined ratio occurs. Therefore, it is generally difficult to efficiently extract light emitted from the light-emitting layer to the outside of the semiconductor light-emitting element.

In particular, when light enters a medium having a large refractive index from a medium having a large refractive index, total light is totally reflected, and light having a critical angle or higher cannot be taken out to the outside. At the interface of the semiconductor light-emitting element, that is, the interface between the air (or sealing material) and the semiconductor element, since the refractive index between the two mediums is large, the critical angle of total reflection is small, and as a result, the proportion of light totally reflected at the interface is increased. .

For example, the sapphire substrate has a refractive index n of 1.8 and a critical angle to air of 33.7 degrees. That is, sapphire is used as a substrate constituting the semiconductor light-emitting element When light is taken out to the air side through the sapphire substrate, light having an incident angle of more than 33.7 degrees is totally reflected and cannot be taken out to the outside. Even in the case of an aluminum nitride (AlN) substrate having a large refractive index (refractive index n = 2.29), the critical angle is 25.9 degrees, and only less light can be taken out to the outside.

The light extraction efficiency of the semiconductor light-emitting element in which the AlGaN layer is laminated on the AlN substrate is calculated using theoretical calculation of the light emission characteristics by the Finite-Difference Time-Domain Method (FDTD method). As a result, the surface of the AlN substrate (light extraction) is taken into consideration from the light having a wavelength of 265 nm emitted from the light-emitting portion in the AlGaN layer and the absorption of the p-type GaN layer on the opposite side to the AlN substrate as seen from the light-emitting portion. The extraction efficiency of light that can be taken out on the side of the surface is extremely low, about 4%.

For such a problem, in order to enhance the light extraction efficiency, a semiconductor light-emitting element having a nano-scale uneven structure on the substrate surface (light extraction surface) has been proposed. For example, in Patent Document 1, it is disclosed that an uneven structure having an average period of twice or less the average optical wavelength of light emitted from the light-emitting layer is provided on the light extraction surface. By forming such a concavo-convex structure, a method of reducing the ratio of the portion of the light that is totally reflected on the light extraction surface (that is, suppressing the reflection of light on the surface of the element) is proposed. However, it is not easy to form a nano-scale uneven structure on the surface of the semiconductor light-emitting element. In addition, depending on the shape of the uneven structure, the wavelength of light emission, and the like, the light extraction efficiency also largely changes, and a sufficient effect cannot be obtained.

The shorter the light-emitting wavelength is, the shorter the period of the desired uneven structure (for example, the convex structure, the distance between the apex portion of the convex structure and the apex portion of the adjacent convex structure) is shorter, and the uneven structure is produced. It becomes difficult. Especially emitting ultraviolet light. Semiconductor light-emitting elements of light in the deep ultraviolet wavelength region In this case, the size of the uneven structure becomes a field in which it is difficult to manufacture by photolithography. As a result, problems such as an increase in production cost, a decrease in yield, and a low yield occur, and there is no practicality.

In order to form a periodic uneven structure of a nanometer scale, a nanometer-scale fine metal in which a vapor-deposited metal is heated and aggregated is formed on a light extraction surface in the patent document 1 (JP-A-2005-354020). A method of masking the surface of the light extraction surface. However, with the periodic mask having such an agglomeration effect, the arrangement of the concavo-convex structure is disordered, and the shape unevenness is large. Therefore, the degree of variation in the power of light output from the semiconductor light emitting element to the outside is large, and it is difficult to provide a semiconductor light emitting element that emits stable and uniform light.

In Non-Patent Document 1 (ISDRS 2011, December 7-9, 2011, College Park, MD, USA, WP2-04), it is disclosed that the surface of the substrate is roughened by wet etching in order to form a concave-convex structure of a nanometer scale. method. However, the uneven structure formed by the wet etching method is also a disordered structure having a non-uniform shape, and the light extraction efficiency greatly fluctuates, and the effect of improving the light extraction efficiency is also insufficient.

In Non-Patent Document 2 (Appl. Phys. Express 3 (2010) 061004), in a semiconductor light-emitting element that emits deep ultraviolet light, a surface periodic uneven structure is provided by lithography or dry etching, but the period of the uneven structure is When the wavelength is 500 nm, the wavelength of the light is twice as large, and the sufficient effect of improving the light extraction efficiency cannot be obtained. In addition, the variability of the light output is also extremely large.

[First technical literature]

[Patent Literature]

[Patent Document 1] JP-A-2005-354020

[Non-patent literature]

[Non-Patent Document 1] ISDRS 2011, December 7-9, 2011, College Park, MD, USA, WP2-04

[Non-Patent Document 2] Appl. Phys. Express 3 (2010) 061004

As described above, a semiconductor light-emitting element having a nano-scale uneven structure on the surface of the substrate (light extraction surface) is proposed for the purpose of improving light extraction efficiency. However, in such a conventional light-emitting element, the uneven structure is provided. The optimum value of the period and the height and shape of the convex portion constituting the uneven structure is not clear and varies depending on the light-emitting wavelength, the refractive index of the substrate, and the like, and it is a state in which a sufficient effect cannot be exhibited. Further, as the emission wavelength becomes a short wavelength, it is necessary to form a concavo-convex structure having a smaller dimension on the surface (light extraction surface) of the substrate, which makes it more difficult to fabricate the concavo-convex structure. Therefore, even if the light-emitting wavelength is a short wavelength, the uneven structure in which the light extraction efficiency is sufficiently improved is formed with good reproducibility, and the power output from the semiconductor light-emitting element to the outside is further uniformized and stabilized. Question.

Therefore, an object of the present invention is to provide a semiconductor light-emitting element which can obtain a light extraction efficiency with high light extraction efficiency and a uniform light output, and can manufacture the semiconductor with high reproducibility and high yield, even if the light-emitting wavelength is short. A method of manufacturing a semiconductor light-emitting device of a light-emitting element.

A semiconductor light emitting device according to the present invention is a semiconductor light emitting element having a semiconductor layer containing a light emitting layer, and a surface of the semiconductor light emitting element includes a light extraction surface. At least one of the interfaces of the two layers having different refractive indices in the light extraction surface and the semiconductor light emitting element is formed with a periodic uneven structure having a period larger than 0.5 times the wavelength of light emitted from the light emitting layer; and fine The uneven structure is located on the surface of the periodic concavo-convex structure and has an average diameter of 0.5 times or less of the wavelength of light.

According to the present invention, a semiconductor light-emitting element which achieves high light extraction efficiency can be obtained.

11‧‧‧ positive electrode

12‧‧‧p-type semiconductor layer

13‧‧‧Active layer

14‧‧‧Negative electrode

15‧‧‧n type semiconductor layer

16‧‧‧Substrate

16A‧‧‧Back

21‧‧‧Cycle relief structure

22‧‧‧Micro-concave structure

D1, D2‧‧‧ diameter

H1‧‧‧ Height

L1‧‧ cycle

S10, S100‧‧‧ substrate preparation steps

S20, S200‧‧‧ semiconductor layer formation steps

S30, S300‧‧‧ electrode formation steps

S40, S400‧‧‧ concave and convex structure forming steps

S41‧‧‧ Cover forming steps

S42, S420‧‧‧ etching steps

S43‧‧‧ Mask removal steps

S410‧‧‧ Etching mask production steps

S430‧‧‧ Etching mask removal steps

Fig. 1 is a schematic cross-sectional view showing a first embodiment of a semiconductor light emitting device according to the present invention.

Fig. 2 is a plan schematic view showing a light extraction surface of the semiconductor light emitting element shown in Fig. 1.

Fig. 3 is a partial cross-sectional schematic view of line segment III-III in Fig. 2;

Fig. 4 is a plan schematic view for explaining a modification of the semiconductor light emitting element shown in Fig. 1.

Fig. 5 is a flow chart for explaining a method of manufacturing the semiconductor light emitting element shown in Fig. 1.

Fig. 6 is a plan schematic view showing a second embodiment of the semiconductor light emitting device according to the present invention.

Fig. 7 is a partial cross-sectional schematic view of line VII-VII of Fig. 6.

Fig. 8 is a plan schematic view for explaining a modification of the semiconductor light emitting element shown in Fig. 6.

Fig. 9 is a flow chart for explaining a method of manufacturing the semiconductor light emitting element shown in Fig. 6.

Fig. 10 is a plan view schematically showing a semiconductor light emitting element used as a sample of Example 1.

Fig. 11 is a schematic cross-sectional view of the line segment XI-XI of Fig. 10.

Fig. 12 is a scanning electron micrograph of the light extraction surface of the semiconductor light emitting element shown in Fig. 10.

Fig. 13 is a scanning electron micrograph of the light extraction surface of the semiconductor light emitting element shown in Fig. 10.

Fig. 14 is a graph showing the results of the experiment of Example 1.

Fig. 15 is a scanning electron micrograph of the light extraction surface of the semiconductor light emitting element used as the sample of Example 2.

Fig. 16 is a scanning electron micrograph of the light extraction surface of the semiconductor light emitting element used as the sample of Example 2.

Fig. 17 is a scanning electron micrograph of the light extraction surface of the semiconductor light emitting element used as the sample of Example 2.

Fig. 18 is a graph showing the results of the experiment of Example 1.

Fig. 19 is a graph showing the results of the simulation calculation of the third embodiment.

Fig. 20 is a graph showing the results of the simulation calculation of Example 3.

Fig. 21 is a graph showing the results of the simulation calculation of Example 4.

Fig. 22 is a graph showing the results of the simulation calculation of Example 4.

Fig. 23 is a graph showing the results of the experiment of Example 5.

Fig. 24 is a graph showing the results of the experiment of Example 6.

Fig. 25 is a graph showing the experimental results of Example 7.

Fig. 26 is a graph showing the results of experiments of Example 8 and Example 9.

Figure 27 is a graph showing experimental values and simulation calculation results in the examples.

[Formation for implementing the invention]

First, an outline of the form of implementation will be described.

(1) The semiconductor light-emitting device according to the present embodiment is a semiconductor light-emitting device having a semiconductor layer including a light-emitting layer (active layer 13), and the surface of the semiconductor light-emitting device includes a light extraction surface. At least one of the interfaces of the two layers having different refractive indices in the light extraction surface and the semiconductor light emitting element is formed with a periodic uneven structure 21 having a period larger than 0.5 times the wavelength of light emitted from the light emitting layer; The fine concavo-convex structure 22 is located on the surface of the periodic concavo-convex structure 21 and has an average diameter of 0.5 times or less of the wavelength of light.

In this case, the periodic concavo-convex structure 21 having a period corresponding to the wavelength (emission wavelength) of the light emitted from the light-emitting layer and the fine concavo-convex structure 22 having an average diameter corresponding to the wavelength are formed in the light extraction surface, and there is no In comparison with the case of these uneven structures, the light extraction efficiency can be surely improved. In other words, even in the case of forming a periodic uneven structure having a period larger than the wavelength, the light extraction efficiency can be sufficiently improved by combining with the fine uneven structure. Further, when the light-emitting wavelength is a short wavelength (for example, 450 nm or less or 350 nm or less), the semiconductor light-emitting device according to the present embodiment has an effect of suppressing an increase in cost associated with the production of the periodic uneven structure. In addition, since it can be formed at a period larger than the emission wavelength of the periodic uneven structure, the formation of a uniform uneven structure becomes uniform. easy.

(2) In the above semiconductor light emitting element, the arrangement pattern of the periodic uneven structure 21 may be a triangular lattice shape. At this time, the number of the convex portions of the periodic concavo-convex structure 21 per unit area can be easily increased.

(3) In the above semiconductor light emitting device, the periodic concavo-convex structure 21 may include a convex portion (convex portion) composed of a high refractive index material portion having a refractive index higher than that of air. The cross-sectional area of the convex portion on the surface perpendicular to the direction from the light-emitting layer (active layer 13) to the light extraction surface (back surface 16A of the substrate 16) can be made smaller as it goes away from the light-emitting layer (active layer 13). If the external medium of the light extraction surface is air, the light extraction efficiency from the light extraction surface can be surely improved.

(4) In the above semiconductor light emitting element, the shape of the convex portion may be a pyramid shape or a semi-elliptical spherical shape. At this time, the convex portion can be easily formed using a relatively general process such as etching.

(5) In the above semiconductor light emitting element, the light emitting layer may contain a group III nitride semiconductor. The semiconductor layer may include: an n-type group III nitride semiconductor layer (n-type semiconductor layer 15) having a conductivity type of n-type; and a p-type group III nitride semiconductor layer (p-type semiconductor layer 12) having a conductivity type of p-type, Located on the opposite side of the n-type group III nitride semiconductor layer as seen from the light-emitting layer. When such a group III nitride semiconductor is used, a semiconductor light-emitting element that emits light of a so-called short wavelength having an emission wavelength of 450 nm or less can be obtained.

(6) The semiconductor light-emitting device may have a transparent substrate disposed on the side from the light-emitting layer to the light extraction surface and having transparency to light emitted from the light-emitting layer. At this time, the back surface of the transparent substrate (the back surface opposite to the main surface on which the semiconductor layer is formed) can be used as the light extraction surface.

(7) In the above semiconductor light emitting device, the transparent substrate may be an aluminum nitride substrate. At this time, the defect density of the semiconductor layer containing the light-emitting layer composed of the group III nitride semiconductor can be greatly reduced.

(8) In the above semiconductor light emitting element, the wavelength of light emitted from the light emitting layer may be 450 nm or less. When such an emission wavelength is a short wavelength, the effects as described above can be remarkably obtained.

(9) In the semiconductor light-emitting device, the height H1 of the periodic concavo-convex structure 21 may be 1/3 times or more and 5 times or less with respect to the period L1 of the periodic concavo-convex structure 21; and the average height of the fine concavo-convex structure 22 is relative to the fine concavo-convex structure The average diameter of 22 may be 0.1 times or more and 10 times or less. At this time, the light extraction efficiency can be surely improved.

(10) The semiconductor light emitting device according to the present embodiment includes: a substrate 16 made of aluminum nitride; and a semiconductor layer formed on a main surface of the substrate 16. The semiconductor layer includes a light-emitting layer (active layer 13) containing a group III nitride semiconductor, an n-type group III nitride semiconductor layer (n-type semiconductor layer 15) having a conductivity type in which a light-emitting layer is interposed, and a conductive type. It is a p-type p-type group III nitride semiconductor layer (p-type semiconductor layer 12). The wavelength of light emitted from the light-emitting layer is 350 nm or less. On the back surface of the substrate 16 on the opposite side to the main surface, a periodic concavo-convex structure 21 having a period in which the wavelength of light emitted from the light-emitting layer is divided by the refractive index of the aluminum nitride constituting the substrate is formed is formed. The value (measured value) of the difference in refractive index of the external medium located outside the substrate is 1/3 times or more and 5 times or less.

At this time, it is determined by the wavelength (light emission wavelength) of light emitted from the light-emitting layer, the refractive index of the substrate 16 composed of AlN, and the refractive index of the external medium. The period of the periodic concavo-convex structure 21 can surely improve the light extraction efficiency from the back surface (light extraction surface) of the substrate 16.

Further, the period is preferably 0.5 times or more and 4 times or less, more preferably 1 time or more and 3 times or less the evaluation value.

(11) In the above semiconductor light emitting device, the arrangement pattern of the periodic uneven structure 21 may be a triangular lattice shape. At this time, the number of the convex portions of the periodic concavo-convex structure 21 per unit area can be easily increased.

(12) In the above semiconductor light emitting device, the periodic concavo-convex structure includes a convex portion, and the shape of the convex portion may be a pyramid shape or a semi-elliptical spherical shape. At this time, the convex portion can be easily formed using a relatively general process such as etching.

(13) In the semiconductor light-emitting device, the height of the periodic concavo-convex structure may be 1/3 times or more and 5 times or less with respect to the period of the periodic concavo-convex structure. At this time, the light extraction efficiency can be surely improved.

Further, the height is preferably 0.5 times or more and 2 times or less, more preferably 0.6 times or more and 1.8 times or less.

(14) A method of manufacturing a semiconductor light-emitting device according to the present embodiment, comprising the steps of: preparing an element member to be a semiconductor light-emitting element including a semiconductor layer having a light-emitting layer; and the element member immediately becoming the semiconductor light-emitting element A mask layer having a pattern is formed on the light extraction surface; and the mask layer is used as a mask to partially remove the region to be the light extraction surface by etching, thereby forming a periodic uneven structure. The mask layer is a metal mask layer. In the step of forming the periodic concavo-convex structure, a periodic uneven structure is formed by dry etching using a fluorine-based gas as an etching gas, and in the step of removing the residue of the mask layer, a surface of the periodic concavo-convex structure is formed. micro- Fine concave and convex construction. The periodic concavo-convex structure has a period exceeding 0.5 times the wavelength of light emitted from the luminescent layer. The fine concavo-convex structure has an average diameter of 0.5 times or less of the wavelength of light. Further, the periodic concavo-convex structure and the fine concavo-convex structure are characterized by the same material. If so, the semiconductor light emitting element according to the embodiment can be easily obtained.

(15) A method of manufacturing a semiconductor light-emitting device according to the present embodiment, comprising the steps of: preparing an element member to be a semiconductor light-emitting element, wherein the semiconductor light-emitting element comprises a substrate made of aluminum nitride, and a main surface formed on the substrate And a semiconductor layer having a light-emitting layer; in the element member, a mask layer having a pattern is formed on a region to be a light extraction surface of the semiconductor light-emitting element; and a mask is used as a mask to partially shift by etching In addition to the above-described region which is to be the light extraction surface, a periodic uneven structure is formed thereby. The periodic concavo-convex structure has a period in which the wavelength of light emitted from the light-emitting layer is divided by more than 1/3 times the value of the difference between the refractive index of the aluminum nitride constituting the substrate and the refractive index of the external medium located outside the substrate. , 5 times or less. If so, the semiconductor light emitting element according to the embodiment can be easily obtained.

(16) In the above semiconductor light-emitting device, the period of the periodic concavo-convex structure 21 may be one time or more of the wavelength of light. At this time, the periodic uneven structure 21 can be easily manufactured.

(17) In the above semiconductor light-emitting device, the period of the periodic concavo-convex structure 21 may be twice or more the wavelength of light. Further, the average diameter of the fine concavo-convex structure 22 may be 0.4 times or less the wavelength of light. At this time, an increase in the manufacturing cost of the semiconductor light emitting element can be avoided, and the light extraction efficiency can be surely improved.

(18) In the above semiconductor light emitting element, the transparent substrate may be blue Gem substrate. Even with such a configuration, a semiconductor light emitting element having improved light extraction efficiency can be obtained.

(19) In the above semiconductor light emitting device, the wavelength (light emission wavelength) of light emitted from the light emitting layer may be 350 nm or less. At this time, the effect of the present embodiment is remarkable in the semiconductor light-emitting device that emits light of a short wavelength as described above.

Next, a specific example of the form of the embodiment of the invention will be described with reference to the appropriate drawings. However, the light-emitting elements described below are intended to embody the technical idea of the present invention, and are not intended to limit the present invention to the following elements. In particular, the dimensions, materials, shapes, relative positions, and the like of the constituent members disclosed below are not intended to limit the scope of the present invention to the above-described case, and are merely illustrative examples, unless otherwise specified. In addition, the size, positional relationship, and the like of the components shown in the respective drawings may be exaggerated for clarity of explanation. Further, each of the elements constituting the present invention may be configured such that a plurality of elements are formed by the same part, and a plurality of elements are used as one part, or a function of realizing one part by a plurality of parts may be shared. In addition, the respective embodiments disclosed below can be applied in the same manner as long as there is no particular exclusion.

(Form 1 of implementation)

Figs. 1 to 3 are conceptually showing the structure of a semiconductor light emitting element according to the first embodiment of the present invention. Referring to FIGS. 1 to 3, the semiconductor light-emitting device mainly has a substrate 16 made of AlN (aluminum nitride), an n-type semiconductor layer 15, an active layer 13, a p-type semiconductor layer 12, a positive electrode 11 and a negative electrode 14. On the main surface of the substrate 16, an n-type semiconductor layer 15 is formed. Partial table of the n-type semiconductor layer 15 A convex portion is formed on the surface, and an active layer 13 is formed on the convex portion. On the active layer 13, a p-type semiconductor layer 12 is formed. On the p-type semiconductor layer 12, a positive electrode 11 is formed. Further, on the surface of the n-type semiconductor layer 15, a negative electrode 14 is formed in a region where the above-described convex portion is not formed.

The wavelength of light emitted from the active layer 13 as the light-emitting layer is 350 nm or less. On the substrate 16, on the back surface on the opposite side to the main surface, a periodic concavo-convex structure 21 having a period L1 which is the wavelength of light emitted from the active layer 13 divided by the nitrogen constituting the substrate 16 is formed. The value of the difference between the refractive index of the aluminum and the refractive index of the external medium located outside the substrate 16 (reference value) is 1/3 times or more and 5 times or less.

Hereinafter, each component will be individually described.

<Substrate>

As the substrate 16, a substrate which can epitaxially grow a nitride semiconductor crystal on the surface and which has a high transmittance in a wavelength region of light emitted from the semiconductor light-emitting device (for example, a light transmittance of 50% or more) can be selected. . For example, examples of the material of the substrate 16 include the above-described AlN, and even sapphire, GaN, and the like.

As described above, the substrate 16 has a periodic uneven structure 21 formed on the light extraction surface (back surface). Specifically, the periodic concavo-convex structure 21 includes a convex shape portion having a pyramid shape as shown in FIGS. 2 and 3 (for example, a diameter D1 having a bottom surface, a height H1 from a bottom surface to a vertex, and a side surface and The shape of the cone formed by the bottom surface θ). Further, the shape of the convex portion may be a semi-elliptical spherical shape as shown in Fig. 4 .

In addition, the arrangement of the periodic concavo-convex structures (arrangement of the convex shape portions) may be a periodic arrangement method such as a triangular lattice arrangement, a square lattice arrangement, or a hexagonal lattice arrangement, and is preferably a triangular lattice row having a maximum filling factor (filling factor). Column. Further, the periodic concavo-convex structure 21 may have a value which is a value obtained by dividing the emission wavelength of the semiconductor light-emitting element by the difference between the refractive index of the aluminum nitride constituting the substrate 16 and the refractive index of the air of the external medium located outside the substrate 16. A period L1 of 1/3 times or more and 5 times or less (reference value). Further, the height H1 of the periodic concavo-convex structure 21 is preferably in the range of 1/3 times or more and 5 times or less with respect to the period L1.

In addition, the period L1 of the periodic concavo-convex structure 21 is preferably 0.5 times or more and 4 times or less of the above reference value, and more preferably 1 time or more and 3 times or less. If so, the light extraction efficiency can be improved more reliably. In addition, the height H1 of the periodic concavo-convex structure 21 is preferably 0.5 times or more and 2 times or less, more preferably 0.6 times or more and 1.8 times or less with respect to the period L1. If so, the light extraction efficiency can be improved more reliably.

Next, a method of producing the periodic concavo-convex structure 21 will be described below. The periodic concavo-convex structure 21 can be fabricated by the following processes: first, etching mask making step (step (S41) of FIG. 5); second, etching step (step (S42) of FIG. 5); third, mask Screen removal step (step (S43) of Fig. 5). The etching mask manufacturing step is a step of forming an etching mask pattern on the back surface of the substrate 16, and any method such as an electron beam lithography method, a photolithography method, or a nanoimprint lithography method can be applied. In addition, in order to increase the etching selectivity ratio in the etching step, a patterned mask pattern (for example, a resist mask) is formed by any of the above methods, and the metal pattern is deposited to cover the mask pattern, and then lifted off. A part of the metal is removed together with the mask pattern to create a metal mask pattern.

The mask pattern is used as an etching mask to etch the back surface of the substrate 16, and a desired pattern is formed on the back surface of the substrate 16. The etching method can be performed by dry etching using inductively coupled plasma (ICP) etching, reactive ion etching (RIE), or the like. An acidic solution or an alkaline solution is used as a wet etching or the like of the etching solution. Here, in order to form a pattern having a high periodicity, dry etching is preferably applied. In the etching step using the dry etching, a resin material such as a resist or the like, a metal or the like can be used as the etching mask, and as the etching gas, a chlorine-based gas, a fluorine-based gas, a bromine-based gas or the like can be applied. Further, a gas such as hydrogen or oxygen may be mixed in the etching gas described above.

After the above etching step, a mask removal step is performed. That is, the residue of the etching mask is removed. The method of removing the residue of the etching mask can be appropriately determined by etching the material of the mask. For example, if the material of the etching mask is metal, an acidic solution having a solubility in the metal or an alkaline solution may be used to remove the residue.

Further, on the periodic concavo-convex structure 21, a sealing material such as resin, glass, or quartz can be formed. Further, on the surface of the sealing material, a concavo-convex structure can be formed. The configuration of the uneven structure can be the same as that of the periodic uneven structure 21 described above.

<Laminated semiconductor layer>

The laminated semiconductor layer is composed of a group III nitride semiconductor. As shown in FIG. 1, the n-type semiconductor layer 15, the active layer 13, and the p-type semiconductor layer 12 are sequentially laminated on the substrate 16. The laminated semiconductor layer is an organometallic chemical vapor deposition method (MOCVD method), an organometallic vapor phase epitaxy method (MOVPE method), a molecular beam epitaxy method (MBE method), a hydride vapor phase epitaxy method (HVPE method). ) Equal stacking.

N-type semiconductor layer:

The n-type semiconductor layer 15 is preferably made of Al _x In _y GaN _z (x, y, z are rational numbers satisfying 0<x≦1.0, 0≦y≦0.1, 0≦z<1.0 and x+y+z=1.0 The semiconductor layer is composed of n-type impurities. The impurity is not particularly limited, and examples thereof include bismuth (Si), germanium (Ge), and tin (Sn). Preferred examples thereof include Si and Ge. The concentration of the n-type impurity may be 1.0 × 10 ¹⁷ /cm ³ or more and 1.0 × 10 ²⁰ /cm ³ or less. Further, from the viewpoint of both the crystallinity and the contact property of the n-type semiconductor layer 15, the concentration of the n-type impurity is preferably 1.0 × 10 ¹⁸ /cm ³ or more and 1.0 × 10 ¹⁹ /cm ³ or less.

Further, the thickness of the n-type semiconductor layer 15 is 100 nm or more and 10000 nm or less. Moreover, from the viewpoint of both the crystallinity and the contact property of the n-type semiconductor layer 15, the film thickness of the n-type semiconductor layer 15 is preferably 500 nm or more and 3,000 nm or less.

Active layer:

The active layer 13 has a multiple quantum well configuration. The active layer 13 is composed of a laminated structure of two layers of alternating layers: Al _x In _y GaN _z (x, y, z are satisfying 0<x≦1.0, 0≦y≦0.1, 0≦z<1.0) a well layer composed of rational numbers and x+y+z=1.0); and Al _x In _y GaN _z with energy gap energy greater than the energy gap energy of the well layer (x, y, z satisfy 0<x≦1.0, A barrier layer composed of 0≦y≦0.1, a rational number of 0≦z<1.0, and x+y+z=1.0). The film thickness of the well layer is 1 nm or more, preferably 2 nm or more. The film thickness of the barrier layer is 1 nm or more, preferably 2 nm or more.

P-type semiconductor layer:

The p-type semiconductor layer 12 is composed of, for example, a p-type cladding layer and a p-type contact layer. The p-type cladding layer is composed of Al _x In _y GaN _z (x, y, z are rational numbers satisfying 0<x≦1.0, 0≦y≦0.1, 0≦z<1.0, and x+y+z=1.0). . Since it is necessary to encapsulate the electrons into the active layer 13, it is preferable that the energy gap energy of the p-type cladding layer is larger than the energy gap energy of the semiconductor layer constituting the active layer 13. Therefore, the Al component of the p-type cladding layer is preferably larger than the Al component of the semiconductor layer constituting the active layer 13.

As the impure substance of the p-type coating layer, magnesium (Mg) is preferably used. The concentration (doping concentration) of Mg is 1.0 × 10 ¹⁷ /cm ³ or more, preferably 1.0 × 10 ¹⁷ /cm ³ or more. The film thickness of the p-type cladding layer is 5 nm or more and 1000 nm or less, preferably 10 nm or more and 50 nm or less.

The p-type contact layer is composed of Al _x In _y GaN _z (x, y, and z are rational numbers satisfying 0<x≦1.0, 0≦y≦0.1, 0≦z<1.0, and x+y+z=1.0). The Al component of the p-type contact layer is preferably smaller than the Al component of the p-type cladding layer. The reason is that the energy gap energy of the p-type contact layer is smaller than that of the p-type cladding layer, and good contact characteristics are easily obtained. As the impurity of the p-type contact layer, as the p-type coating layer, magnesium (Mg) is preferably used. The doping concentration of Mg may be 1.0 × 10 ¹⁷ /cm ³ or more. The film thickness of the p-type contact layer is from 1 nm to 50 nm, preferably from 5 nm to 30 nm, from the viewpoint of the transmittance of ultraviolet light and the contact property with the p-type contact layer.

<negative electrode layer>

The negative electrode 14 is an exposed surface (the upper surface surrounding the convex portion of the n-type semiconductor layer 15) formed on the n-type semiconductor layer 15. The exposed surface of the n-type semiconductor layer 15 is formed by partially removing (for example, removing by etching or the like) a part of the n-type semiconductor layer 15 and the active layer 13, the p-type semiconductor layer 12, and the like. As the etching method, dry etching such as reactive ion etching or inductively coupled plasma etching can be applied. After the exposed surface of the n-type semiconductor layer 15 is formed, in order to remove the portion of the n-type semiconductor layer 15 which is damaged by etching on the surface to be etched (exposed surface), it is preferred to apply a surface treatment with an acidic or alkaline solution. Thereafter, a negative electrode 14 having an ohmic property is formed on the exposed surface of the n-type semiconductor layer 15.

Patterning of the electrodes of the negative electrode 14, the positive electrode 11, etc., can be used Implement the law of separation. Specifically, after the photoresist is applied to the electrode forming surface, the photoresist is locally irradiated with ultraviolet rays by a UV exposure machine having a photomask. Thereafter, the photoresist is immersed in the developer to form a resist film of a desired pattern by dissolving the photosensitive photoresist. A metal film to be an electrode is deposited on the resist film that has been patterned. Then, the resist film is dissolved in a stripping solution, and the metal film on the resist film is removed, whereby the metal film in the region where the resist film is not formed remains, forming a metal film (electrode) having a predetermined pattern.

As the patterning method of the electrode, the following methods can also be cited. That is, a metal film to be an electrode is formed on the electrode forming surface (for example, the exposed surface of the n-type semiconductor layer 15). Then, after applying a photoresist on the metal film, the photoresist is patterned by exposure and development steps. Thereafter, the metal film is partially removed by dry etching or wet etching using the patterned photoresist (resist film) as a mask. Thereafter, the photoresist was dissolved in a stripping solution. In this way, an electrode can also be formed. Further, the above-described lift-off method is more suitable for the step of forming a resist pattern on the metal film because of the simple steps.

The method of depositing the metal film constituting the negative electrode 14 may be any method such as a vacuum deposition method, a sputtering method, or a chemical vapor deposition method. However, from the viewpoint of eliminating impurities in the metal film, vacuum evaporation is preferably used. law. The material used for the negative electrode 14 can be exemplified by various materials and can be selected from known materials. After depositing the metal film to be the negative electrode 14, in order to improve the contact between the n-type semiconductor layer 15 and the negative electrode 14, it is preferable to heat at a temperature of 300 ° C or more and 1100 ° C or less for 30 seconds or more and 3 minutes or less. The conditions of time are heat treated. The temperature and the heating time of the heat treatment may be carried out under appropriate optimum conditions depending on the type of the metal constituting the negative electrode 14 and the film thickness of the metal film.

<positive electrode layer>

The positive electrode 11 is formed on the p-type contact layer in the p-type semiconductor layer 12. For the patterning of the positive electrode 11, it is preferable to use the lift-off method in the same manner as the patterning of the negative electrode 14. The material used for the positive electrode 11 can be selected from various materials and can be selected from known materials. Further, since the positive electrode 11 is preferably light transmissive, the thinner the thickness of the positive electrode 11 is preferably. Specifically, the thickness of the positive electrode 11 is 10 nm or less, and more preferably 5 nm or less.

As a method of depositing a metal film to be the positive electrode 11, as in the formation of the negative electrode 14, any method such as a vacuum deposition method, a sputtering method, or a chemical vapor deposition method can be used, but in order to eliminate the metal film as much as possible. As the impurity, it is preferred to use a vacuum evaporation method. After the metal film to be the positive electrode 11 is deposited, in order to improve the contact with the p-type contact layer, it is preferred to apply heat treatment at a temperature of 200 ° C or higher and 800 ° C or lower for 30 seconds or longer and 3 minutes or shorter. The temperature and time of the heat treatment may be appropriately selected under the conditions of the type of the metal constituting the positive electrode 11 and the thickness of the positive electrode 11.

The above semiconductor light emitting element is manufactured by the manufacturing process as shown in Fig. 5. That is, referring to Fig. 5, the substrate preparation step (S10) is first performed. In this step (S10), a substrate composed of AlN is prepared. Further, the periodic concavo-convex structure 21 has not been formed on the back surface of the substrate at this stage. Next, a semiconductor layer forming step (S20) is performed. In this step (S20), a laminated semiconductor layer composed of the p-type semiconductor layer 12, the active layer 13, and the n-type semiconductor layer 15 is formed on the main surface of the substrate 16. Each of the p-type semiconductor layer 12, the active layer 13, and the n-type semiconductor layer 15 can be formed by any method such as MOCVD method or MOVPE method as described above.

Next, an electrode forming step (S30) is performed. In this step, The p-type semiconductor layer 12 and a portion of the active layer 13n-type semiconductor layer 15 are removed by etching, whereby the exposed surface of the n-type semiconductor layer 15 is formed as shown in FIG. Further, the positive electrode 11 is formed on the p-type semiconductor layer 12 by the lift-off method or the like, and the negative electrode 14 is formed on the exposed surface of the n-type semiconductor layer 15.

Thereafter, a concavo-convex structure forming step (S40) is performed. In this step (S40), the mask forming step (S41) is first performed. In this step (S41), an etching mask pattern is formed on the back surface of the substrate 16 by lithography or the like as described above. Next, an etching step (S42) is performed. In this step (S42), the back surface of the substrate 16 is etched by using the above-described etching mask pattern as a mask. As a result, the periodic concavo-convex structure 21 is formed. Then, the mask removal step (S43) is carried out next. In this step (S43), the residue of the etching mask is removed by any method. In this way, the semiconductor light emitting element shown in Fig. 1 can be obtained.

(Form 2 of implementation)

In the semiconductor light-emitting device according to the second aspect of the present invention, the substrate has the same structure as the semiconductor light-emitting device shown in FIGS. 1 to 3, but the rear surface of the substrate 16 has the same structure as that of the first to third semiconductors. The light emitting elements are different. Fig. 6 is a plan view schematically showing the back surface of the substrate 16 of the semiconductor light-emitting device according to the second aspect of the present invention. Referring to Fig. 6, in the semiconductor light-emitting device of the second embodiment of the present invention, the back surface of the substrate 16 is used as an example of the light extraction surface, and the periodic uneven structure 21 is formed on the back surface of the substrate 16. Then, a fine uneven structure 22 is further formed on the surface of the periodic uneven structure 21.

That is, the semiconductor light emitting element shown in Fig. 6 is a semiconductor layer having an active layer 13 which is a light emitting layer and a semiconductor light emitting element. The surface includes the back surface of the substrate 16 as a light extraction surface. At least one of the interfaces of the two layers having different refractive indices in the light extraction surface and the semiconductor light emitting element is formed with a periodic uneven structure 21 having a period L1 larger than 0.5 times the wavelength of light emitted from the active layer 13 And the fine concavo-convex structure 22 is located on the surface of the periodic concavo-convex structure 21, and has an average diameter (average value of the diameter D2) of 0.5 times or less of the wavelength of light. Further, the average diameter is a diameter of the fine concavo-convex structure 22 included in the square region in which the length of one cycle of the periodic concavo-convex structure 21 is measured, and can be determined by the average value of those diameters.

In addition, the back surface of the substrate 16 is used as an example of the light extraction surface, and the periodic uneven structure 21 and the like are formed on the back surface 16A of the substrate 16 as an example. However, the periodic uneven structure 21 and the fine uneven structure 22 are formed. The location is not limited to the light extraction surface. In other words, the places where the periodic uneven structure 21 and the fine uneven structure 22 are formed may be any interface between layers having different refractive indices in the semiconductor light emitting element. For example, when another member such as a sealing material is formed on the back surface 16A of the substrate 16, the interface between the back surface 16A and the sealing material (other member) or the layer having a different refractive index such as a semiconductor layer in the semiconductor light emitting element may be used. The periodic uneven structure 21 and the fine uneven structure 22 are formed by an interface or the like.

Further, if another member such as a sealing material is formed on the back surface of the substrate 16 as described above, the surface of the sealing material (the surface of the other member) becomes a light extraction surface for the outside. Further, in this case, in addition to the interface having the largest difference in refractive index (for example, the interface between the back surface 16A and the sealing member (other member)), the periodic uneven structure 21 and the fine portion may be formed in the portion of the surface of the sealing material which becomes the light extraction surface. Concave structure 22.

Semiconductor light-emitting device according to the embodiment, p-type semiconductor layer 12. The structure of the active layer 13, the n-type semiconductor layer 15, the positive electrode 11, and the negative electrode 14 is basically the same as that of the semiconductor light-emitting elements shown in FIGS. 1 to 3, and the configuration of the substrate 16 is as described above. The semiconductor light-emitting elements shown in FIGS. 1 to 3 are different. Therefore, the configuration of the substrate 16 will be described.

<Substrate>

The material, characteristics, and the like of the substrate 16 are basically the same as those of the substrate 16 in the semiconductor light-emitting device shown in FIGS. 1 to 3, and for example, sapphire, AlN, GaN, or the like can be used. The substrate 16 has a periodic concavo-convex structure 21 on the light extraction surface (back surface) as described above. Specifically, the periodic concavo-convex structure 21 includes a convex shaped portion which has a tapered shape as shown in FIGS. 6 and 7. Further, the shape of the convex portion may be a semi-elliptical spherical shape as shown in Fig. 8.

Further, the arrangement of the periodic concavo-convex structures 21 may be a periodic arrangement method such as a triangular lattice arrangement, a square lattice arrangement, or a hexagonal lattice arrangement, and is preferably a triangular lattice arrangement in which the filling factor is the largest. Further, the periodic concavo-convex structure 21 may have a period L1 that is in a range of more than 0.5 times the emission wavelength of the semiconductor light emitting element. In addition, the height H1 of the periodic concavo-convex structure 21 (the height H1 of the convex shaped portion) is preferably in the range of 1/3 times or more and five times the period L1.

As an example of the numerical range of the period L1 of the periodic concavo-convex structure 21, for example, it may be 2/3 times or more and 1000 times or less, or 2 times or more and 100 times or less of the above-mentioned light emission wavelength. If so, the light extraction efficiency can be more surely improved, and at the same time, the manufacturing cost can be suppressed, and a more uniform element shape and light output can be obtained. In addition, the height H1 of the periodic concavo-convex structure 21 is preferably 1/2 times or more and 3 times or less, more preferably 3/4 times or more and 2 times or less with respect to the period L1. If so, the light extraction efficiency can be improved more surely, and the manufacturing can be suppressed. In this way, a more uniform component shape and light output can be obtained.

Further, on the back surface of the substrate 16 on which the periodic concavo-convex structure 21 is formed, a fine concavo-convex structure 22 smaller than the periodic concavo-convex structure 21 is formed on the surface of the periodic concavo-convex structure 21. The fine concavo-convex structure 22 is a concave portion (a flat portion located between the convex portions) that is disposed on the surface of the convex portion of the periodic concavo-convex structure 21 and the periodic concavo-convex structure 21 . The average diameter of the fine concavo-convex structure 22 is 1/2 or less of the emission wavelength of the semiconductor light-emitting device, and the height of the fine concavo-convex structure 22 is preferably in the range of 0.1 times or more and 10 times or less of the average diameter. Further, the height of the fine concavo-convex structure 22 is preferably 0.2 times or more and 5 times or less, more preferably 0.5 times or more and 2 times or less. The fine convex portion of the fine concavo-convex structure 22 preferably has a pyramidal shape or a semi-elliptical spherical shape.

The average diameter of the fine concavo-convex structure 22 is more preferably 1/30 times or more and 2/5 times or less, more preferably 1/10 times or more and 3/10 times or less. If so, the light extraction efficiency can be improved more reliably. In addition, the average height of the fine concavo-convex structure 22 is preferably 0.2 times or more and 5 times or less, more preferably 0.5 times or more and 2 times or less with respect to the average diameter. If so, the light extraction efficiency can be improved more reliably.

In addition, the average height of the fine concavo-convex structure 22 is a height of a fine concavo-convex structure included in a square region having a length of one cycle of the periodic concavo-convex structure, and can be determined by the average value of those heights.

Next, a method of producing the uneven structure will be described below. The periodic concavo-convex structure 21 and the fine concavo-convex structure 22 can be produced by the following processes: first, an etching mask making step (step (S410) of FIG. 9); second, etching step (step of FIG. 9 (S420) )); third, etching mask removal step (step of Figure 9) Step (S430)). The etching mask manufacturing step is a step of forming an etching mask pattern on the substrate, and an electron beam lithography method, a photo lithography method, a nanoimprint lithography method, or the like can be applied. In addition, in order to increase the etching selectivity ratio in the etching step, after forming a patterned mask pattern (for example, a resist mask) by any of the above methods, a metal is deposited to cover the mask pattern, and then The lift method removes a portion of the metal along with the mask pattern to create a metal mask pattern.

Here, in the formation of the fine concavo-convex structure 22, it is preferable to form a mask for metal by lift-off method, and it is more preferable to form a mask for metal by a nickel film. The reason is that the nickel particles etched in the etching step (S420) or the reaction product of nickel and the etching gas adheres to the back surface of the substrate 16, and acts as a nano-sized etching mask to reliably form the fine uneven structure 22.

The mask pattern is used as an etching mask to etch the back surface of the substrate 16 to form a desired pattern on the back surface of the substrate 16. The etching method may be dry etching using inductively coupled plasma (ICP) etching, reactive ion etching (RIE), or wet etching using an acidic solution or an alkaline solution as an etching solution. Here, in order to form a pattern having a high periodicity, dry etching is preferably applied.

In the etching step using dry etching, a resin material such as a resist or the like, a metal or the like can be used as an etching mask. Further, as the reaction gas of the etching gas, a chlorine-based gas, a fluorine-based gas, a bromine-based gas, or the like is preferably used, and a gas such as hydrogen, oxygen, or argon may be mixed with the etching gas. Moreover, in order to form the fine uneven structure 22, it is preferable to use a fluorine-based gas as a dry etching gas, in particular, a fluorine-containing gas containing carbon.

Alternatively, before the mask manufacturing step, the back surface of the substrate 16 may be roughened in advance by dry etching, wet etching, or the like. At this point, here The periodic uneven structure 21 is formed by the above-described process on the rough surface, and the combination of the periodic uneven structure 21 and the fine uneven structure 22 can be produced.

Further, after the periodic concavo-convex structure 21 is formed, fine particles such as metal or ceramic may be disposed on the back surface of the substrate 16 (the surface on which the periodic concavo-convex structure 21 is formed), and dry etching may be performed using the fine particles as an etching mask. In this way, a combination of the periodic concavo-convex structure 21 and the fine concavo-convex structure 22 can be produced. The method of disposing the fine particles may be a method of applying a solvent in which fine particles are dissolved on the back surface of the substrate 16 and drying the film, and a method of forming a metal thin film on the back surface of the substrate 16 and then heating the metal thin film to agglomerate the metal thin film. Any method can be used.

As described above, there are various methods for producing the periodic uneven structure 21 and the fine uneven structure 22. However, in view of the simplicity of the process, it is preferable to etch the metal mask with a fluorine-containing gas containing carbon.

After the etching step, the residue of the etching mask is removed as a mask removal step. For the method of removing the residue of the etching mask, the method shown in the first embodiment can be used.

Further, on the combination of the periodic concavo-convex structure 21 and the fine concavo-convex structure 22, a sealing portion such as resin, glass, or quartz can be formed. Further, a combination of the periodic concavo-convex structure 21 and the fine concavo-convex structure 22 or the periodic concavo-convex structure 21 or the fine concavo-convex structure 22 can be formed on the surface of the sealing portion.

The semiconductor light-emitting device according to the above-described embodiment is manufactured by the process described in FIG. That is, referring to Fig. 9, the substrate preparation step (S100) to the electrode formation step (S300) are carried out. These steps (S100) to (S300) can basically be carried out in the same manner as the steps (S10) to (S30) shown in Fig. 5.

Thereafter, a concave-convex structure forming step (S400) is performed. In this step (S400), first, a mask forming step (S410) is performed. In this step (S410), an etching mask pattern made of metal is formed on the back surface of the substrate 16 by lithography or the like as described above. Next, an etching step (S420) is performed. In this step (S420), the back surface of the substrate 16 is etched by the carbon-containing fluorine-based gas using the etching mask pattern as a mask. As a result, the periodic concavo-convex structure 21 and the fine concavo-convex structure 22 are formed. Then, the mask removal step (S430) is carried out next. In this step (S430), the residue of the etching mask is removed by any method. In this way, the semiconductor light emitting element shown in Fig. 6 can be obtained.

Further, the periodic concavo-convex structure 21 and the fine concavo-convex structure 22 may not be formed on the back surface of the substrate 16, but may form an interface of two layers having different refractive indices in the semiconductor light-emitting device. At this time, the light emitted from the luminescent layer is also reduced at this interface. The ratio of total reflection, as a result, can improve the light extraction efficiency of the semiconductor light emitting element.

Here, the characteristic configuration of the present invention will be partially overlapped with the above-described embodiment.

In other words, in the same state of the present invention, when the surface of the semiconductor light-emitting device (the back surface 16A of the substrate 16 or another member such as a sealing material is placed on the back surface 16A of the substrate 16), the surface of the other member is used. An interface between the layers of the light-receiving surface or the layers having different refractive indices in the semiconductor light-emitting device (for example, an interface between the back surface 16A and the resin when a resin or the like is placed on the back surface 16A of the substrate 16 or in the semiconductor light-emitting device) In the semiconductor layer or the like, the interface between the layers having different refractive indices, etc., the periodic uneven structure 21 having a period exceeding 0.5 times the emission wavelength and the fine uneven structure 22 having an average diameter of 1/2 or less with respect to the emission wavelength. , formed together on the same surface (or interface).

At this time, the fine uneven structure 22 having a smaller dimension than the periodic uneven structure is formed on the flat surface portion of the gap between the periodic uneven structures 21 and the surface of the periodic uneven structure 21, and the periodic uneven structure 21 is present as a single body. Can be more moderate on the surface. The refractive index difference of the interface suppresses reflection, total reflection, and the like.

Further, in the case where the periodic concavo-convex structure 21 is single, in general, in order to improve the light extraction efficiency, it is necessary to form a small-scale periodic concavo-convex structure 21 having a wavelength or less; and in the configuration of the present embodiment, even if the size is larger than the wavelength By combining with the fine concavo-convex structure 22, the periodic concavo-convex structure 21 can sufficiently improve the light extraction efficiency. That is, even if the emission wavelength is a short wavelength, it is easy to produce a uniform structure by reducing the cost of fabrication of the light extraction structure and adding a process window.

Further, the arrangement pattern of the periodic concavo-convex structure 21 is preferably a triangular lattice shape.

Further, it is preferable that the shape of the periodic concavo-convex structure 21 is such that the cross-sectional area of the high refractive index medium decreases as it goes from the bottom to the vertex direction (light extraction direction).

Further, the shape of the periodic concavo-convex structure 21 is a convex shape, and the convex shape is preferably a pyramid shape or a semi-elliptical spherical shape.

The same state of the present invention has the following features, but the present invention is not limited to the following aspects.

A semiconductor layer having an n-type group III nitride semiconductor layer (n-type semiconductor layer 15), a group III nitride semiconductor light-emitting layer (active layer 13), and a p-type group III nitride semiconductor layer (p-type semiconductor layer 12) The product structure is characterized.

Having a flip chip structure and emitting from a group III nitride semiconductor The transparent layer (substrate 16) having transparency to the light emission wavelength from the light layer to the light extraction surface side is characterized.

The transparent substrate is characterized by an aluminum nitride (AlN) substrate or a sapphire substrate.

It is characterized by an emission wavelength of 450 nm or less or 350 nm or less.

The height of the periodic concavo-convex structure 21 is in the range of 1/3 to 5 times the period, and the average height of the fine concavo-convex structure 22 is in the range of 1/10 to 5 times the average diameter.

Further, another aspect of the present invention is characterized by comprising an AlN substrate (substrate 16), an n-type group III nitride semiconductor layer (n-type semiconductor layer 15), a group III nitride semiconductor light-emitting layer (active layer 13), and p The semiconductor layered structure of the group III nitride semiconductor layer (p-type semiconductor layer 12) has an emission wavelength of 350 nm or less, and is formed on the surface of the AlN substrate to have a refractive index with respect to the emission wavelength / (the refractive index of the AlN substrate and the external medium) The periodic uneven structure 21 of the period of the range of 1/3 to 5 times the difference in the rate.

Further, the arrangement pattern of the periodic concavo-convex structure 21 is preferably a triangular lattice shape.

Further, the shape of the periodic concavo-convex structure 21 is a convex shape, and the convex shape is preferably a pyramid shape or a semi-elliptical spherical shape.

Further, the height of the periodic concavo-convex structure 21 is preferably in the range of 1/3 to 5 times the period.

Further, another aspect of the present invention is characterized in that it is a method of manufacturing the above semiconductor light-emitting element, comprising the steps of: periodically processing an organic film; forming an metal mask using an organic film (organic film); The periodic uneven structure 21 is formed by dry etching.

Further, the present invention is characterized in that the periodic uneven structure 21 and the fine uneven structure 22 are simultaneously formed by dry etching using a metal mask and a fluorine-based gas.

At this time, by using a metal mask and a dry etching method of a fluorine-based gas, since it can be artificially uniform. The periodic uneven structure is produced in a high-purity manner, and the acid treatment for peeling off the metal mask by dry etching is performed, and the surface is formed on the flat surface of the gap between the periodic uneven structures and the surface of the periodic uneven structure 21, and the like. The fine concavo-convex structure 22 having a scale much smaller than the wavelength can simultaneously form the periodic concavo-convex structure 21 and the fine concavo-convex structure 22 in one process. By this, you can be uniform. The periodic concavo-convex structure 21 having a size or wavelength equal to or greater than the wavelength and the shape change greatly affecting the characteristics is produced with high precision; and the scale can be spontaneously and densely formed to be much smaller than the wavelength, and the shape change does not greatly affect the characteristics. Fine concavo-convex structure 22. Further, the periodic concavo-convex structure 21 and the fine concavo-convex structure 22 are characterized by the same material. As a result, the uniformity of the processed shape and the reproducibility of the process can be improved, and the light extraction efficiency and the uniformity thereof can be improved, and the manufacturing cost can be suppressed to a low level.

According to the present invention, by combining the periodic uneven structure 21 having different dimensions and the fine uneven structure 22, reflection, total reflection, and the like on the substrate surface (light extraction surface), the interface, and the like are effectively suppressed. Further, under the scalable process range, even if the emission wavelength is a short wavelength, a semiconductor light-emitting element capable of obtaining high light extraction efficiency and uniform light output can be produced with high reproducibility and throughput. Further, in the method of manufacturing the periodic concavo-convex structure 21 and the fine concavo-convex structure 22, it is possible to improve the uniformity of the processed shape and the reproducibility of the process. While improving the light extraction efficiency and its uniformity, the manufacturing cost is suppressed at a low level.

[Example 1]

According to the structure of the semiconductor light-emitting device according to the above-described embodiment of the present invention, as shown in FIGS. 10 and 11, a semiconductor light-emitting device according to the first embodiment is produced. Specifically, on the substrate 16 made of single crystal AlN, the n-type semiconductor layer 15, the active layer 13 (light-emitting layer), and the p-type semiconductor layer 12 are sequentially grown by MOCVD to obtain a light-emitting element substrate, and the light-emitting element substrate is obtained. In the element substrate, the positive electrode 11 and the negative electrode 14 are arranged at predetermined positions. The epitaxial layer of the light-emitting layer including the semiconductor light-emitting device is composed of the same AlGaN-based semiconductor as that of the above-described embodiment, and the light-emitting wavelength of the device is 265 nm.

An electron beam resist is applied to a substrate surface (light extraction surface) on the opposite side of the epitaxial layer of the fabricated semiconductor light-emitting device substrate, and the electron beam is aligned by covering the light-emitting portion of the semiconductor light-emitting device. Depicting, making an etched mask pattern. The light-emitting portion is a circular region having a diameter of 100 μm, and the center of the light-emitting portion is the center of the drawing, and the drawing region is set to 900 μm × 900 μm. The drawing pattern was set to have a diameter of 220 nm and a pattern period of 300 nm, and the pattern arrangement was set to a triangular lattice arrangement. Next, on the etching mask pattern, nickel of 100 nm to 500 nm is deposited by vacuum evaporation. The reason for depositing nickel is as described in the above-described embodiment, in order to improve the etching selectivity of the substrate 16 and the etching mask pattern. After the deposition of nickel, the semiconductor light-emitting device substrate is immersed in the stripping liquid of the electron beam resist to remove the resist and the nickel on the resist (lifting method). In this manner, a mask pattern made of nickel is formed on the back surface of the substrate 16.

Next, the semiconductor light-emitting device substrate was introduced into an ICP etching apparatus, and an etching treatment was performed for 10 minutes to 30 minutes using a trifluoromethane (CHF ₃ ) gas. Thereafter, in order to remove the mask pattern of nickel, the semiconductor light-emitting device substrate was immersed in hydrochloric acid at 20 ° C to 30 ° C for 15 minutes. In this case, in order to prevent the electrode metal of the semiconductor light-emitting device substrate from being corroded by hydrochloric acid, the electrode forming surface of the semiconductor light-emitting device substrate is coated with a photoresist and then cured to be used as a protective film. After immersing in hydrochloric acid, the semiconductor light-emitting device substrate was washed with ultrapure water, and the photoresist as a protective film was dissolved in a stripping solution.

Thus, the ultraviolet light-emitting semiconductor light-emitting device of Example 1 having the funnel structure having a cone-shaped bottom portion having a diameter of 250 nm, a period L1 of 300 nm, and a height H1 of 250 nm was formed. Scanning electron micrographs of the produced concavo-convex structures are shown in Figs. 12 and 13.

A semiconductor light-emitting element (Comparative Example 1) of ultraviolet light emission before the formation of the uneven structure on the substrate 16 was prepared as a comparative example with respect to Example 1. Then, the light output was measured for the samples of these Examples and Comparative Example 1. The results are shown in Fig. 14.

Referring to Fig. 14, the horizontal axis represents the light output ratio of the embodiment in the case of Comparative Example 1, and the vertical axis represents the number of samples. When the light output of Comparative Example 1 was 1.00, the average value of the light output ratio of the Example was 1.31. Fig. 14 is a histogram showing the light output ratio of the ultraviolet light-emitting semiconductor light-emitting device of the sample of Example 1. Further, the standard deviation of the light output ratio of Example 1 was 0.031, which was equivalent to 2.3% of the average value of the light output ratio. That is, the sample of Example 1 showed a semiconductor light-emitting element having a very small variation in light-emitting output.

[Example 2]

A semiconductor light-emitting device according to Example 2 was produced based on the structure of the semiconductor light-emitting device according to the above-described embodiment of the present invention. In addition, implementation The configuration of the semiconductor light-emitting device of Example 2 is basically the same as that of the semiconductor light-emitting device of Example 1. In other words, on the substrate 16 made of single crystal AlN, the n-type semiconductor layer 15, the active layer 13 (light-emitting layer), and the p-type semiconductor layer 12 are sequentially grown by MOCVD to obtain a light-emitting element substrate. The substrate has the positive electrode 11 and the negative electrode 14 disposed at predetermined positions. The epitaxial layer of the light-emitting layer including the semiconductor light-emitting device is composed of the same AlGaN-based semiconductor as that of the above-described embodiment, and the light-emitting wavelength of the device is 265 nm.

An electron beam resist is applied to a substrate surface (light extraction surface) on the opposite side of the light-emitting element layer of the fabricated semiconductor light-emitting device wafer, and is made electronic by aligning the light-emitting portion of the semiconductor light-emitting device The beam is drawn to create an etched mask pattern. The light-emitting portion is a circular region having a diameter of 100 μm, and the center of the light-emitting portion is the center of the drawing, and the drawing region is set to 900 μm × 900 μm. The drawing pattern was set to have a diameter of 300 nm and a pattern period of 600 nm, and the pattern arrangement was set to a regular triangular lattice arrangement. Next, on the mask pattern, nickel of 100 nm to 500 nm is deposited by vacuum evaporation. The reason for depositing nickel is the same as that described in the first embodiment. After the deposition of nickel, the semiconductor light-emitting device substrate is immersed in the stripping liquid of the electron beam resist to remove the resist and the nickel on the resist (lifting method). In this manner, a mask pattern made of nickel is formed on the back surface of the substrate 16.

Next, the semiconductor light-emitting device substrate was introduced into an ICp etching apparatus, and an etching treatment was performed for 30 minutes to 80 minutes using a trifluoromethane (CHF ₃ ) gas. By adjusting the thickness of the nickel film and the etching time, it is controlled whether or not the fine concavo-convex structure and shape are formed. Finally, in order to remove the mask pattern of nickel, the semiconductor light-emitting device substrate was immersed in hydrochloric acid heated to 60 ° C to 90 ° C for 15 minutes. In this case, in order to prevent the electrode metal of the semiconductor light-emitting device substrate from being corroded by hydrochloric acid, the electrode forming surface of the semiconductor light-emitting device substrate is coated with a photoresist and then cured to be used as a protective film. After immersing in hydrochloric acid, it was washed with ultrapure water, and the photoresist as a protective film was dissolved in a stripping solution.

Thus, an ultraviolet light-emitting semiconductor light-emitting device of Example 2 having a periodic concavity and convex structure having a diameter of 600 nm, a period of 600 nm, and a height of 550 nm and a fine concavo-convex structure having an average diameter of 52 nm and an average height of 52 nm was formed. Scanning electron micrographs of the produced concavo-convex structures are shown in Figures 15-17. As shown in Fig. 17, the fine concavo-convex structure is distributed more densely on the concave portion of the periodic concavo-convex structure than on the convex portion of the periodic concavo-convex structure.

A semiconductor light-emitting element (Comparative Example 2) of ultraviolet light emission before the uneven structure was formed on the substrate was prepared as a comparative example with respect to Example 2. Then, the light output was measured for the samples of Example 2 and Comparative Example 2. The results are shown in Fig. 18.

Referring to Fig. 18, the horizontal axis represents the light output ratio of the second embodiment in the case of Comparative Example 2, and the vertical axis represents the number of samples. When the light output of Comparative Example 2 was 1.00, the average value of the light output ratio of Example 2 was 1.70. In addition, when the ultraviolet light-emitting semiconductor light-emitting device having only the fine uneven structure was used as Comparative Example 3, the average value of the light output ratio of Comparative Example 3 with respect to Comparative Example 2 was 1.25. As a result, the superiority of the structure having both the periodic uneven structure and the fine uneven structure produced in Example 2 can be exhibited. Fig. 18 is a histogram showing the light output ratio of the ultraviolet light-emitting semiconductor light-emitting device of the sample of Example 2. Further, the standard deviation of the light output ratio of Example 2 was 0.029, which corresponded to 1.7% of the average value of the light output ratio of Example 2. That is, the sample of Example 2 is also shown to be A semiconductor light-emitting element having a very small variation in light-emitting output.

[Example 3]

In order to confirm the efficacy of the periodic uneven structure 21 formed in the semiconductor light emitting element according to the present invention, the following simulation calculation was performed. In other words, the light emitted from the AlGaN layer as the light-emitting layer (wavelength: 265 nm) is calculated by the AlN substrate and the periodic uneven structure (the secondary element period arrangement (triangular lattice) of the cone made of AlN) processed on the surface of the AlN substrate. The light extraction efficiency of the outside (air) is taken out. In addition, the light extraction efficiency in the case where the same system has no periodic uneven structure is also calculated.

The calculation uses the finite difference time domain method (FDTD method) to set the dipole point source as the initial source, but calculates and averages (quasi-disordered) by artificially changing the direction and position of the dipole. The way to reproduce a non-coherent light source. The refractive index is assumed to be 2.43 for the AlGaN portion, 2.29 for the AlN portion, and 1.0 for the air portion. The opposite side (back side) from the light extraction surface as viewed from the light-emitting layer is normally absorbed by the p-GaN layer as an absorption boundary. The results are shown in Fig. 19 and Fig. 20.

19 and 20 are diagrams for calculating a periodic concavo-convex structure (a quadratic periodic arrangement of a cone made of AlN) which is formed by processing an AlGaN substrate and a surface of an AlN substrate by light emitted from an AlGaN layer as a light-emitting layer (wavelength: 265 nm). (Triangular lattice)) The light extraction efficiency of the outside (air) is taken out, and the numerical value (light output ratio) normalized by the result of the case (planar) without the periodic uneven structure is displayed. The width of the bottom of the convex portion (conical portion) of the periodic uneven structure is set to coincide with the period. The horizontal axis of Fig. 19 shows the period (unit: nm) of the periodic uneven structure, and the vertical axis shows the light output ratio. In Figure 19, each aspect with a different aspect ratio is displayed. Data for a situation. Further, the horizontal axis of Fig. 20 shows the aspect ratio (the ratio of the height of the bottom portion of the convex portion (conical portion) of the periodic concavo-convex structure to the width of the convex portion), and the vertical axis indicates the light output ratio. In Fig. 20, data of each period (a) of the periodic uneven structure is shown.

Referring to Fig. 19, in the range of 200 nm to 450 nm, the light output ratio becomes maximum when the aspect ratio is 1.0. In addition, please refer to Fig. 20, and the light output ratio becomes maximum when the aspect ratio is 1.0.

In addition, the 19th and 20th figures are the results of the calculation of the binary element, but it is confirmed that the result is almost the same as the calculation of the three-dimensional element.

[Embodiment 4]

In order to confirm the efficacy of the periodic uneven structure 21 formed in the semiconductor light emitting element according to the present invention, the following simulation calculation was performed. In other words, the light emitted from the AlGaN layer as the light-emitting layer (wavelength: 265 nm) is calculated by the AlN substrate and the periodic uneven structure (the secondary element period arrangement (triangular lattice) of the cone made of AlN) processed on the surface of the AlN substrate. The light extraction efficiency of the outside (sealing material layer) is taken out. In addition, the light extraction efficiency in the case where the same system has no periodic uneven structure is also calculated. In addition, the calculation method is the same as that of the third embodiment. The refractive index is assumed to be 2.43 for the AlGaN portion, 2.29 for the AlN portion, and 1.45 for the sealing material portion. As the sealing material portion, SiO ₂ , a resin, or the like is set. The other conditions were the same as in the third embodiment.

21 and 22 are diagrams for calculating a periodic concavo-convex structure (a quadratic lattice arrangement of a cone made of AlN) by processing an AlGaN substrate and a surface of an AlN substrate by a light emitted from an AlGaN layer (wavelength: 265 nm). ) and the light extraction efficiency of the outside (sealing material layer) is taken out, and there is no circumference on the surface of the AlN substrate. In the case where the plane of the period of the uneven structure is taken out to the outside (air layer), the normalized value (light output ratio) of the calculation result of the light extraction rate is displayed.

The horizontal axis of Fig. 21 shows the period (unit: nm) of the periodic uneven structure, and the vertical axis shows the light output ratio. In Fig. 21, data of each case in which the aspect ratio is different is displayed. In addition, the horizontal axis of Fig. 22 shows the aspect ratio, and the vertical axis shows the light output ratio. In Fig. 22, the data of each period (a) of the periodic uneven structure is shown.

According to the results of the third embodiment and the fourth embodiment, it is understood that the optimum light extraction structure differs depending on the refractive index of the external medium such as the sealing member even in the case of, for example, the same substrate, wavelength, and periodic uneven structure. However, the extraction of light from the AlN substrate and the periodic concavo-convex structure processed on the surface of the AlN substrate is advantageous for the production step in the case of taking out the air or the sealing material layer, and based on these results, the periodic uneven structure 21 can be confirmed. The effect.

[Embodiment 5]

A semiconductor light-emitting device according to Example 5 was produced based on the structure of the semiconductor light-emitting device according to the above-described embodiment of the present invention. Further, the configuration of the semiconductor light-emitting device of the fifth embodiment is basically the same as that of the semiconductor light-emitting device of the first embodiment. The epitaxial layer of the light-emitting layer including the semiconductor light-emitting device is composed of the same AlGaN-based semiconductor as that of the above-described embodiment, and the light-emitting wavelength of the device is 265 nm.

Applying an electron beam resist to a substrate surface (light extraction surface) opposite to the light-emitting element layer of the fabricated semiconductor light-emitting device wafer, and aligning the light-emitting portion of the semiconductor light-emitting device to form an electron beam Depicting, making an etched mask pattern. The light-emitting portion is a circular region having a diameter of 100 μm, and the center of the light-emitting portion is the center of the drawing, and the drawing region is set to 900 μm × 900 μm. The drawing is set to straight The diameter is 180 nm, the pattern period is 300 nm, and the pattern arrangement is set to a triangular lattice arrangement. Next, on the mask pattern, nickel of 100 nm to 500 nm is deposited by vacuum evaporation. The reason for depositing nickel is the same as that described in the first embodiment. After the deposition of nickel, the semiconductor light-emitting device substrate is immersed in the stripping liquid of the electron beam resist to remove the resist and the nickel on the resist (lifting method). In this manner, a mask pattern made of nickel is formed on the back surface of the substrate 16.

Next, in the same manner as in Example 2, the semiconductor light-emitting device substrate was introduced into an ICP etching apparatus, and an etching treatment was performed for 10 minutes to 80 minutes using a trifluoromethane (CHF ₃ ) gas. As in the case of the embodiment 5 and the embodiment 2, the etching process time is relatively short. Finally, in order to remove the mask pattern of nickel, the semiconductor light-emitting device substrate was immersed in hydrochloric acid heated to 60 ° C to 90 ° C for 15 minutes. Further, by adjusting the temperature of the hydrochloric acid, it is possible to control whether or not a fine uneven structure and shape are formed. In the same manner as in the case of the second embodiment, in order to prevent the electrode metal of the semiconductor light-emitting device substrate from being corroded by hydrochloric acid, the electrode forming surface of the semiconductor light-emitting device substrate is coated with a photoresist and then cured to be used as a protective film. After immersing in hydrochloric acid, it was washed with ultrapure water, and the photoresist as a protective film was dissolved in a stripping solution.

Thus, an ultraviolet light-emitting semiconductor light-emitting device of Example 5 having a periodic concavo-convex structure having a diameter of 300 nm, a period of 300 nm, and an aspect ratio of 1, and a fine concavo-convex structure having an average diameter of 33 nm and an average height of 33 nm was prepared.

The ultraviolet light-emitting semiconductor light-emitting device before the formation of the uneven structure on the substrate was prepared as Comparative Example 4 as a comparative example with respect to Example 5. Then, the light output was measured for the samples of Example 5 and Comparative Example 4. Show the results In Figure 23.

Referring to Fig. 23, the horizontal axis represents the light output ratio of Example 5 in the case of Comparative Example 4, and the vertical axis represents the number of samples. When the light output of Comparative Example 4 was 1.00, the average value of the light output ratio of Example 5 was 1.96. As understood from Fig. 23, the high light output ratio obtained in Example 5 can show the superiority of the structure having both the periodic uneven structure and the fine uneven structure. Further, the standard deviation of the light output ratio of Example 5 was 0.07, which corresponds to 3.6% of the average value of the light output ratio. Thus, the sample of Example 5 also showed that it was a semiconductor light-emitting element having a relatively small degree of variation in light-emitting output.

[Embodiment 6]

A semiconductor light-emitting device according to Example 6 was produced based on the structure of the semiconductor light-emitting device according to the above-described embodiment of the present invention. Further, the configuration of the semiconductor light-emitting device of the sixth embodiment is basically the same as that of the semiconductor light-emitting device of the first embodiment. Further, the material of the epitaxial layer of the light-emitting layer including the semiconductor light-emitting element and the light-emitting wavelength of the element were the same as those of the above-described fifth embodiment.

An etching mask pattern was produced by electron beam drawing in the same manner as in Example 5 on the substrate surface (light extraction surface) opposite to the light-emitting element layer of the fabricated semiconductor light-emitting device wafer. The light-emitting portion is a circular region having a diameter of 100 μm, and the center of the light-emitting portion is the center of the drawing, and the drawing region is set to 900 μm × 900 μm. The drawing pattern was set to have a diameter of 200 nm and a pattern period of 400 nm, and the pattern arrangement was set to a regular triangular lattice arrangement. Next, in the same manner as in Example 5, nickel of 100 nm to 500 nm was deposited by vacuum evaporation on the mask pattern. After the deposition of nickel, the semiconductor light-emitting device substrate is immersed in the stripping liquid of the electron beam resist to remove the resist and the nickel on the resist (lifting method). In this way, a cover made of nickel is formed on the back surface of the substrate 16. Curtain graphics.

Next, in the same manner as in Example 2, the semiconductor light-emitting device substrate was introduced into an ICP etching apparatus, and an etching treatment was performed for 10 minutes to 80 minutes using a trifluoromethane (CHF ₃ ) gas. Finally, in order to remove the mask pattern of nickel, the semiconductor light-emitting device substrate was immersed in hydrochloric acid heated to 60 ° C to 90 ° C for 15 minutes. In the same manner as in the case of the second embodiment, in order to prevent the electrode metal of the semiconductor light-emitting device substrate from being corroded by hydrochloric acid, the electrode forming surface of the semiconductor light-emitting device substrate is coated with a photoresist and then cured to be used as a protective film. After immersing in hydrochloric acid, it was washed with ultrapure water, and the photoresist as a protective film was dissolved in a stripping solution.

Thus, an ultraviolet light-emitting semiconductor light-emitting device of Example 6 having a periodic concave-convex structure having a diameter of 400 nm, a period of 400 nm, and an aspect ratio of 1, and a fine concavo-convex structure having an average diameter of 33 nm and an average height of 33 nm was formed.

The ultraviolet light-emitting semiconductor light-emitting device before the formation of the uneven structure on the substrate was prepared as Comparative Example 5 as a comparative example with respect to Example 6. Then, the light output was measured for the samples of Example 6 and Comparative Example 5. The results are shown in Fig. 24.

Referring to Fig. 24, the horizontal axis is the light output ratio of Example 6 in the case of Comparative Example 5, and the vertical axis is the number of displayed samples. When the light output of Comparative Example 5 was 1.00, the average value of the light output ratio of Example 6 was 1.79. As is understood from Fig. 24, in the same manner as in the fifth embodiment, the high light output ratio was obtained in the sixth embodiment, and the superiority of the structure having both the periodic uneven structure and the fine uneven structure was exhibited. Further, as understood from Fig. 24, the sample of Example 6 was also shown to be a semiconductor having a relatively small variation in luminescence output as in the sample of Example 5. Optical component.

[Embodiment 7]

A semiconductor light-emitting device according to Example 7 was produced based on the structure of the semiconductor light-emitting device according to the above-described embodiment of the present invention. Further, the configuration of the semiconductor light-emitting device of the seventh embodiment is basically the same as that of the semiconductor light-emitting device of the first embodiment. Further, the material of the epitaxial layer of the light-emitting layer including the semiconductor light-emitting element and the light-emitting wavelength of the element were the same as those of the above-described fifth embodiment.

An etching mask pattern was produced by electron beam drawing in the same manner as in Example 5 on the substrate surface (light extraction surface) opposite to the light-emitting element layer of the fabricated semiconductor light-emitting device wafer. The light-emitting portion is a circular region having a diameter of 100 μm, and the center of the light-emitting portion is the center of the drawing, and the drawing region is set to 900 μm × 900 μm. The drawing pattern is set to have a diameter of 400 nm and a pattern period of 1000 nm, and the pattern arrangement is set to be a triangular lattice arrangement. Next, in the same manner as in Example 5, nickel of 100 nm to 500 nm was deposited by vacuum evaporation on the mask pattern. After the deposition of nickel, the semiconductor light-emitting device substrate is immersed in the stripping liquid of the electron beam resist to remove the resist and the nickel on the resist (lifting method). In this manner, a mask pattern made of nickel is formed on the back surface of the substrate 16.

Next, in the same manner as in Example 2, the semiconductor light-emitting device substrate was introduced into an ICP etching apparatus, and an etching treatment was performed for 10 minutes to 80 minutes using a trifluoromethane (CHF ₃ ) gas. Further, as in the configuration in which the pattern size of the embodiment 5 is small, the etching processing time is short; conversely, in the configuration in which the pattern size of the embodiment 7 is relatively large, the etching processing time becomes long.

Finally, in order to remove the mask pattern of nickel, the semiconductor light-emitting device substrate was immersed in hydrochloric acid heated to 60 ° C to 90 ° C for 15 minutes. In addition, and In the case of the second embodiment, in order to prevent the electrode metal of the semiconductor light-emitting device substrate from being corroded by hydrochloric acid, the electrode-forming surface of the semiconductor light-emitting device substrate is coated with a photoresist and then cured to be used as a protective film. After immersing in hydrochloric acid, it was washed with ultrapure water, and the photoresist as a protective film was dissolved in a stripping solution.

Thus, an ultraviolet light-emitting semiconductor light-emitting device of Example 7 having a periodic concave-convex structure having a diameter of 1000 nm, a period of 1000 nm, and an aspect ratio of 1 and a fine concavo-convex structure having an average diameter of 33 nm and an average height of 33 nm was prepared.

The ultraviolet light-emitting semiconductor light-emitting device before the formation of the uneven structure on the substrate was prepared as Comparative Example 6 as a comparative example with respect to Example 7. Then, the light output was measured for the samples of Example 7 and Comparative Example 6. The results are shown in Fig. 25.

Referring to Fig. 25, the horizontal axis is the light output ratio of Example 7 in the case of Comparative Example 6, and the vertical axis is the number of displayed samples. When the light output of Comparative Example 6 was 1.00, the average value of the light output ratio of Example 7 was 1.69. As is understood from Fig. 25, in the same manner as in the fifth embodiment, the high light output ratio was obtained in the seventh embodiment, and the superiority of the structure having both the periodic uneven structure and the fine uneven structure was exhibited. Further, as is understood from Fig. 25, the sample of Example 7 was also shown as a semiconductor light-emitting device having a relatively small degree of variation in light-emitting output, similarly to the sample of Example 5.

[Embodiment 8]

The period of the periodic uneven structure (the period of the pattern is 300 nm) which is formed on the light extraction surface of the semiconductor light-emitting device wafer of the first embodiment is 600 nm, and is a semiconductor light-emitting device according to the eighth embodiment. In addition, in order Fix the aspect ratio to 1 so that the diameter and height meet the above graphic period. Further, the semiconductor light-emitting device according to the eighth embodiment is the same as the semiconductor light-emitting device according to the first embodiment except for the pattern period, the diameter, and the height. In addition, the production conditions are the same as in the first embodiment except that the processing time of the etching treatment is 30 minutes to 80 minutes.

In this manner, an ultraviolet light-emitting semiconductor light-emitting device having a substrate having a periodic concave-convex structure of a diameter of 600 nm, a period of 600 nm, and a height of 600 nm having a conical bottom portion was produced as the semiconductor light-emitting device of Example 8.

The ultraviolet light-emitting semiconductor light-emitting device before the formation of the uneven structure on the substrate was prepared as Comparative Example 7 as a comparative example with respect to Example 8. Then, the light output was measured for the samples of Example 8 and Comparative Example 7. The results are shown in Fig. 26.

Referring to Fig. 26, the horizontal axis is the light output ratio of Example 8 in the case of Comparative Example 7, and the vertical axis is the number of displayed samples. When the light output of Comparative Example 7 was 1.00, the average value of the light output ratio of Example 8 was 1.44. Here, Example 2, Example 8 having the same periodic concavo-convex structure (period of 600 nm), and Comparative Example 7 having no periodic concavo-convex structure were compared, and the light output ratio was according to Example 2>Example 8>Comparative Example The order of 7 is decremented, and the superiority of the structure having both the periodic concavo-convex structure and the fine concavo-convex structure can be displayed.

[Embodiment 9]

The period of the periodic uneven structure (the period of the pattern is 300 nm) which is formed on the light extraction surface of the semiconductor light-emitting device wafer of the first embodiment is 1000 nm, and is a semiconductor light-emitting device according to the ninth embodiment. In addition, in order to fix the aspect ratio to 1, the diameter and height are made to conform to the above-described pattern period. In addition, The semiconductor light-emitting device according to the ninth embodiment is the same as the semiconductor light-emitting device according to the first embodiment except for the pattern period, the diameter, and the height. In addition, the production conditions are the same as in the first embodiment except that the processing time of the etching treatment is 30 minutes to 80 minutes.

In this manner, an ultraviolet light-emitting semiconductor light-emitting device having a substrate having a periodic concave-convex structure of a diameter of 1000 nm, a period of 1000 nm, and a height of 1000 nm having a conical bottom portion was produced as the semiconductor light-emitting device of Example 9.

The ultraviolet light-emitting semiconductor light-emitting device before the formation of the uneven structure on the substrate was prepared as Comparative Example 8 as a comparative example with respect to Example 9. Then, the light output was measured for the samples of Example 9 and Comparative Example 8. The results are shown in Fig. 26.

Referring to Fig. 26, the horizontal axis is the light output ratio of Example 9 in the case of Comparative Example 8, and the vertical axis is the number of displayed samples. When the light output of Comparative Example 8 was 1.00, the average value of the light output ratio of Example 9 was 1.26. Here, Comparative Example 8 having the same periodic concavo-convex structure (period of 1000 nm), Example 9, and Comparative Example 8 having no periodic concavo-convex structure were compared, and the light output ratio was according to Example 7>Example 9>Comparative Example The order of 8 is decremented, and the superiority of the structure having both the periodic concavo-convex structure and the fine concavo-convex structure can be displayed.

Further, as shown in Fig. 27, the light output ratios obtained in the above-described first embodiment, the eighth embodiment, and the ninth embodiment were in good agreement with the calculation results shown in the third embodiment. This is a proof of the policy of optimizing the light extraction structure obtained by the simulation calculation. Further, in Fig. 27, the light output ratios obtained for Example 2 and Examples 5 to 7 are also combined and drawn. Further, the horizontal axis of Fig. 27 shows the arrangement period (unit: nm) of the uneven structure, and the vertical axis shows the light output ratio.

As can be understood from Fig. 27, the tendency of the light output ratio to compare the arrangement period of the periodic concavo-convex structure is almost identical to the simulation calculation result. In other words, according to Fig. 27, the increase in the absolute value of the light output ratio is confirmed as a result of the effect of improving the light extraction efficiency due to the addition of the fine uneven structure.

The entire contents of the embodiments and examples disclosed herein are illustrative and should not be construed as limiting. The scope of the present invention is defined by the scope of the claims and the scope of the claims and the scope of the claims.

[Industrial availability]

The present invention is particularly advantageous for use in a semiconductor light emitting element that emits light of a short wavelength.

Claims (14)

A semiconductor light-emitting device having a semiconductor layer including a light-emitting layer, wherein a surface of the semiconductor light-emitting device includes a light extraction surface; and at least one of an interface between the light extraction surface and the semiconductor light-emitting device having a refractive index different from each other includes a periodic concavo-convex structure having a period larger than 0.5 times a wavelength of light emitted from the light-emitting layer; and a fine concavo-convex structure located on a surface of the periodic concavo-convex structure and distributed over the concave portion of the periodic concavo-convex structure The convex portion of the periodic concavo-convex structure is densely formed, and the fine concavo-convex structure has an average diameter of 0.5 times or less of the wavelength of the light. A semiconductor light-emitting device having a semiconductor layer including a light-emitting layer, wherein a surface of the semiconductor light-emitting device includes a light extraction surface; and at least one of an interface between the light extraction surface and the semiconductor light-emitting device having a refractive index different from each other includes a periodic concavo-convex structure having a period larger than a wavelength of light emitted from the light-emitting layer; and a fine concavo-convex structure having an average diameter of 0.5 times or less of a wavelength of the light on a surface of the periodic concavo-convex structure; The light emitted from the light-emitting layer has a wavelength of 350 nm or less. The semiconductor light-emitting device according to claim 1 or 2, wherein the arrangement pattern of the periodic uneven structure is a triangular lattice shape. The semiconductor light-emitting device according to claim 1 or 2, wherein the periodic uneven structure includes a high refractive index material portion having a refractive index higher than air; and a surface perpendicular to a direction from the light emitting layer toward the light extraction surface On The cross-sectional area of the high refractive index material portion is smaller as it goes away from the light-emitting layer. The semiconductor light-emitting device of claim 4, wherein the high refractive index material portion comprises a convex portion composed of a high refractive index material having a refractive index higher than air; and the convex portion has a pyramid shape or a semi-elliptical shape. Ball shape. The semiconductor light-emitting device according to claim 1 or 2, wherein the light-emitting layer contains a group III nitride semiconductor; and the semiconductor layer comprises: an n-type group III nitride semiconductor layer of a conductivity type; and a conductive type The p-type p-type group III nitride semiconductor layer is located on the opposite side of the above-described n-type group III nitride semiconductor layer as seen from the above-mentioned light-emitting layer. The semiconductor light-emitting device according to claim 1 or 2, further comprising a transparent substrate disposed on the side of the light-emitting layer from the light-emitting layer and having transparency to light emitted from the light-emitting layer. The semiconductor light-emitting device according to claim 7, wherein the transparent substrate is an aluminum nitride substrate. The semiconductor light-emitting device according to claim 1, wherein the light emitted from the light-emitting layer has a wavelength of 450 nm or less. The semiconductor light-emitting device according to the first or second aspect, wherein the height of the periodic concavo-convex structure is 1/3 times or more and 5 times or less with respect to a period of the periodic concavo-convex structure; and an average height of the fine concavo-convex structure is relatively The average diameter of the fine concavo-convex structure is 0.1 times or more and 10 times or less. The semiconductor light-emitting device according to claim 1, wherein a wavelength of light emitted from the light-emitting layer is 350 nm or less; and a period of the periodic uneven structure is larger than a wavelength of light emitted from the light-emitting layer. A method of manufacturing a semiconductor light-emitting device, comprising: preparing an element member to be a semiconductor light-emitting element including a semiconductor layer having a light-emitting layer; and forming a pattern on a region of the element member on which a light extraction surface of the semiconductor light-emitting element is formed a mask layer; and the mask layer is used as a mask to partially remove the region forming the light extraction surface by etching, thereby forming a periodic uneven structure; wherein the mask layer is a metal mask layer; In the formation of the periodic concavo-convex structure, the periodic concavo-convex structure is formed by dry etching using a fluorine-based gas as an etching gas, and a fine concavo-convex structure is formed on the surface of the periodic concavo-convex structure; a period of 0.5 times a wavelength of light emitted from the light-emitting layer; the fine uneven structure having an average diameter of 0.5 times or less of a wavelength of the light; and the forming of the periodic uneven structure includes: performing the dry etching and removing the metal cover Curtain layer; the period of the above-mentioned periodic concave-convex structure and the above-mentioned metal mask layer Of the same; the dry etching is performed, the reaction product of the metal mask layer and the etching gas is adhered to form the region of the light extraction surface; and In removing the above metal mask layer, the above metal mask layer is removed by an acid treatment. The method of manufacturing a semiconductor light-emitting device according to claim 12, wherein the metal mask layer comprises a nickel film. The method for producing a semiconductor light-emitting device according to claim 12, wherein the etching gas contains a fluorine-containing gas containing carbon.